While the Discord server appears quite useful it has a bunch of gamification built into it and some incompatibilities with certain platforms.
I've recently been made aware of Zoom video conferencing software.
It's free for groups of up to 100 users for up to 40 mins, and during the crisis it's free beyond that too.
Includes screen sharing, chat and a shared whiteboard.
I've used it with a friend tonight and it's excellent. I think this would be the ideal tool for a group to use while playing a game. It could also facilitate remote role-playing sessions.